Antennas suitable for use in RFID devices include an insulating substrate and a first conductive micropattern disposed on or in the substrate, the first conductive micropattern defining a contiguous mesh conductor. The first conductive micropattern forms an antenna responsive to at least a frequency of 915 MHz, and includes interconnected traces having a trace width in a range from 0.5 to 20 microns. Furthermore, the first conductive micropattern is characterized by an open area fraction of at least 80% or 90%. RFID devices include such an antenna and an integrated circuit configured to transmit and receive signals using the antenna. Cards, such as financial transaction cards or identification cards, include such an antenna carried by a card layer.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An RFID device, comprising: an antenna comprising: an insulating substrate; and a first conductive micropattern disposed on or in the substrate, the first conductive micropattern defining a contiguous mesh conductor; wherein the first conductive micropattern forms an antenna responsive to at least a frequency of 915 MHz; wherein the first conductive micropattern comprises interconnected traces having a trace width in a range from 0.5 to 20 microns; wherein the first conductive micropattern has a thickness of less than 2 microns; and wherein the first conductive micropattern is characterized by an open area fraction of at least 80%; and an integrated circuit configured to transmit and receive signals using the antenna; wherein the antenna is tailored to yield a maximum distance at which an RFID reader operating at 1 Watt radiated power in a 902-928 MHz frequency hopping mode communicates with the device, the maximum distance being less than 30 centimeters or from 2 to 50 centimeters.
2. The device of claim 1 , wherein the open area fraction is at least 90%.
3. The device of claim 1 , wherein the first conductive micropattern is composed of an opaque material comprising a metal.
4. The device of claim 3 , wherein the metal is selected from silver, gold, palladium, platinum, aluminum, copper, nickel, tin, alloys, and combinations thereof.
5. The device of claim 1 , wherein the first conductive micropattern has a thickness in a range from 30 nanometers to 1 micron.
6. The device of claim 1 , wherein the trace width is in a range from 1 to 10 microns.
7. The device of claim 1 , wherein the trace width is in a range from 1.5 to 4 micrometers.
8. The device of claim 1 , wherein the first conductive micropattern is characterized by an effective sheet resistance in a range from 0.1 to 200 ohms/square.
9. The device of claim 1 , wherein the insulating substrate is transparent.
10. The device of claim 1 , wherein the antenna has a visible light transmission value of greater than 70%.
11. The device of claim 1 , wherein the antenna is tailored to yield a maximum distance at which an RFID reader operating at 1 Watt radiated power in a 902-928 MHz frequency hopping mode communicates with the device, the maximum distance being from 2.5 to 30 centimeters.
12. A system comprising the device of claim 1 in combination with a first RFID reader operating at between 0.2 Watt and 5 Watts radiated power at a frequency or frequencies between 860 MHz and 960 MHz, wherein a maximum distance at which the first RFID reader communicates with the device is less than 30 centimeters or from 2 centimeters to 50 centimeters.
13. The device of claim 1 , wherein the maximum distance is less than 5 centimeters.
14. A card, comprising: a card layer; an antenna carried by the card layer; and an integrated circuit configured to transmit and receive signals using the antenna; wherein the antenna comprises a conductive micropattern defining a contiguous mesh conductor, the conductive micropattern forming an antenna responsive to at least a frequency of 915 MHz, the conductive micropattern comprising interconnected traces having a trace width in a range from 0.5 to 20 microns, wherein the first conductive micropattern has a thickness of less than 2 microns; and the conductive micropattern being characterized by an open area fraction of at least 80%; wherein the antenna is tailored to yield a maximum distance at which an RFID reader operating at 1 Watt radiated power in a 902-928 MHz frequency hopping mode communicates with the device, the maximum distance being less than 30 centimeters or from 2 to 50 centimeters.
15. The card of claim 14 , wherein the card layer is light transmissive for visible wavelengths.
16. The card of claim 15 , wherein the open area fraction is in a range from 95 to 98%.
17. The card of claim 14 , wherein the first conductive micropattern is composed of an opaque material comprising a metal selected from silver, gold, palladium, platinum, aluminum, copper, nickel, tin, alloys, and combinations thereof.
18. The card of claim 14 , wherein the first conductive micropattern has a thickness in a range from 30 nanometers to 1 micron.
19. The card of claim 14 , wherein the trace width is in a range from 2 to 5 microns.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
November 17, 2011
April 7, 2015
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